Dynamo electric machine having improved slipring assembly

ABSTRACT

This invention relates to dynamo electric machines. The dynamo electric machine includes a frame which supports a pair of bearings. A rotor shaft is journaled for rotation in the bearings, and carries a rotor assembly. A slipring assembly is also carried by the rotor shaft, and a brush assembly is provided, the brushes of which engage the slipring assembly. One end of the rotor shaft extends beyond one of the bearings, and is formed with an axial bore. The slipring assembly includes an integral spigot which is engaged as an interference fit in the bore in the rotor shaft, the spigot serving to support the slipring assembly on the rotor shaft so that the slipring assembly rotates with the rotor shaft. The slipring assembly is electrically connected to the rotor windings by way of leads which extend through the bearing, and so rotate with the shaft.

United States Patent [72] lnventors Herbert John Thomas Cotton 3,295,04612/1966 Margaira 310/68 X Lea Mount" 195, Alcester Road, 3,184,625 /1960Farison 310/231 X Hollywood; 3,487,249 12/1969 Nicholls et al. 310/235 XRobert l-lemmings, 49 Masters Lane, 3,041 ,484 6/1962 Freer et al.310/68 Halesowen both of England Primary Examiner-Milton O. Hirshfield[21] Appl. No. 1,642

. AS31310!!! Examiner B. A. Reynolds [22] Filed 1970 Attorney- Holman &Stern [45] Patented Sept. 28, 1971 [32] Priority Jan. 13, 1969 [33]Great Britain [31] 1880/69 [54] DYNAMO ELECTRIC MACHINE HAVING ABSTRACT:This invention relates to dynamo electric IMPROVED SLIPRING ASSEMBLYmachines. The dynamo elCCtllC machine includes 11 frame 5 CIaimsSDrawing Figs. WhlCh supports a pair of bearings. A rotor shaft 18ournaled for rotation in the bearings, and carries a rotor assembly. A[52] US. Cl 310/232, s|ipring assemmy is M50 carried by the rotor h ftand a brush 310/68 310/237 assembly is provided, the brushes of whichengage the slipring [51] lnt.Cl H0lv 39/06 assemb|y o end of the rotor hf extends beyond one f [50] Field of Search ..3 /232-237, the bearingsand is f d m, an axia| b The slipring 219, 245, 247, sembly includes anintegral spigot which is engaged as an interference fit in the bore inthe rotor shaft, the spigot serving to support the slipring assembly onthe rotor shaft so that the [56] References Cited slipring assemblyrotates with the rotor shaft. The slipring as- UNITED STATES PATENTSsembly is electrically connected to the rotor windings by way 3,396,5868/1968 Maclin et al. 310/232 X of leads which extend through thebearing, and so rotate with 2,109,991 3/1938 French 310/219 the shaft.

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BY QM ATT RN EYS DYNAMO ELECTRIC MACHINE HAVING IMPROVED SLIPRINGASSEMBLY This invention relates to dynamo electric machines, of the kindincluding a frame supporting a pair of bearings, a rotor shaft joumaledfor rotation in said bearings and carrying a rotor assembly, a slipringassembly carried by the rotor shaft and a brush assembly, the brushes ofwhich engage said slipring assembly.

According to the invention, in a machine of the kind specified one endof said rotor shaft extends beyond one of said bearings and is formedwith an axial bore within which is engaged a spigot integral with saidslipring assembly, said spigot serving to support said slipring assemblyon said rotor shaft for rotation therewith and said slipring assemblybeing electrically connected to said rotor assembly by way of leadswhich extend through said bearing so as to rotate with the shaft.

One example of the invention is illustrated in the accompanying drawingswherein:

FIG. 1 is a sectional view of an alternator,

FIG. 2 is a sectional view on the line B-B in Flg. 1,

FIG. 3 is a sectional view on the line C-C in FIG. 2,

FIG. 4 is a sectional view of the brush assembly shown FIG. 1 and FIG. 5is a prospective view of a slipring retaining clip.

Referring to the drawings, the alternator includes a frame 11 carryingfirst and second bearing assemblies 12, 13. Journaled for rotation inthe bearing assemblies 12, 13 is a rotor shaft 14 which carriesintermediate its ends, between the bearing assemblies 12, 13, a rotorassembly 15. The rotor assembly 15 includes a pair of pole pieces oneach side of a core carrying a rotor winding, and the rotor assembly 15is rotatable with the shaft 14, within a stator assembly 16 carried bythe frame II. The shaft 14 projects at one end from the bearing assembly12 and is adapted to receive a fan, and a pulley through which the rotorshaft is driven. At its opposite end, the rotor shaft 14 projects fromthe bearing assembly 13, the rotor shaft 14 terminating within agenerally cylindrical portion 17 of the frame 11. The end of the rotorshaft 14 remote from the bearing assembly 12 is formed with acylindrical bore within which is received a spigot 19 integral with aslipring unit 18. The slipring unit 18 includes a mounded body includinga plain circular face extending in a plane at right angles to the axisof the shaft 14. Said face of the moulded body of the slipring unit 18includes a central conductive disc 21 which lies within a conductiveannulus 22, the disc 21 being insulated from the annulus 22. The disc 21is concentric with the annulus 22, and the disc 21 and the annulus 22constitute the brush engaging surfaces of the slipring unit. The spigot19 of the slipring unit 18 is of cruciform cross section, and isreceived as an interference fit in the bore in the rotor shaft 14, sothat the slipring unit 18 rotates with the rotor shaft 14. A spring clip(not shown) is engaged between the spigot 19 and the wall of the bore inthe shaft 14, and aids the interference fit between the spigot 19 andthe wall of the bore in the shaft 14, in maintaining the slipring unitI8 in engagement with the shaft 14. Since the bore in the shaft 14 iscylindrical, and the spigot 19 is of cruciform cross section, then fourequiangularly spaced passages are defined between the spigot 19 and thewall of the bore shaft 14. A pair of connecting leads are provided forelectrically interconnecting the annulus 22 and the disc 21 of the unit18 to the rotor winding, and these leads extend through the bearingassembly 13 along a diametrically opposite pair of the passages definedbetween the wall of the bore in the shaft 14 and the spigot 19. At theside of the bearing 13 adjacent the rotor assembly 15, that is to saythe side remote from the unit 18, the leads extend through respectivepassages 23 through which the cylindrical bore in the shaft 14communicates with the exterior of the shaft.

The provision of a face-type slipring assembly which is secured to therotor shaft by engaging a spigot integral with the slipring assembly ina bore in the shaft enables the overall length of the alternator to bekept to a minimum.

The inner end of the portion 17 of the frame 11 is closed by bearingassembly 13, and the outer end of the portion 17 is closed by a mouldedsynthetic resin brush box 24. The brush box 24 is engaged as aninterference fit with the frame 11, the brush box 24 including a pair ofspigots 25 which carry spring clips 26 and which are received as a pushfit in corresponding bores 27 in the frame 11 adjacent the portion 17 ofthe frame 11 (FIG. 4). The brush box 24 includes a pair of integralhollow spigots 28 which extend towards the slipring unit 18, and whichreceive respective brushes 29. The brushes 29 include respectiveconductive carriers 31 which extend through slots in the walls of thespigots 28 and which serve to guide the brushes 29 for sliding movementin the spigots 28. The brushes are urged into engagement with theannulus 22 and the disc 21 of the slipring unit 18 respectively, byrespective compression springs 32 which act between the carriers 31 andthe brush box 24. Each of the carriers 31 has electrically connectedthereto a conductive braid 33 which is electrically connected to arespective terminal secured to the exterior of the brush box 24. Thus,the slipring unit and brushes of the alternator are completely enclosedby a housing defined by the bearing assembly 13, the portion 17 of theframe and the brush box 24.

The alternator is a three-phase alternator, and is provided with a fullwave rectifier. The full wave rectifier includes a pair of arcuateterminal plates 34, 35 each of which includes a pair of portionsindicated by the suffixes a and b which are interconnected by aconductive integral neck indicated by the suffix c. The plates 35, 36are arranged with the portion 35b of the plate 35 between the portions36a, 36b of the plate 36, and the portion 36b of the plate 36 betweenthe portions 35a, 35b of the plate 35. The plate 35 carries three diodes37, 38, 39, with their anodes electrically connected to the plate 35 andin heat exchange relationship therewith. The diode 37 is carried by theportion 35a of the plate 35 while the diodes 38, 39 are carried by theportion 35b of the plate 35. Similarly, the plate 36 carries threediodes 41, 42, 43 with their cathodes electrically connected to theplates 36, and in heat exchange relationship therewith, the diode 41being carried by the portion 36a of the plate 36 while the diodes 42, 43are carried by the portion 36b of the plate 36. The portion 36a of theplate 36 includes a lug which overlaps a corresponding lug at one end ofthe portion 35b of the plate 35, at its opposite end the portion 35b ofthe plate 35 includes a lug which overlaps a cor responding lug at oneend of the portion 36b of the plate 36, and at its other end the portion36b of the plate 36 includes a lug which overlaps a corresponding lug onthe portion 35a of the plate 35. The plates 35, 36 are secured to oneanother by means of bolts 44, 45, 46 which extend through the lugs ofthe plates 35, 36 respectively. The lugs of the plates 35, 36 areinsulated from one another by insulating washers, and the bolt 45 isinsulated from both of the plates 35, 36. The bolt 45 physicallyconnects the plates 35, 36 to the frame 11 of the alternator and afurther pair of bolts 47 connected to but insulated from the plates 35,36 respectively aid the bolt 45 in securing the plates 35, 36 to theframe 11. The bolt 44 is electrically connected to the plate 35, butinsulated from the plate 36, while the bolt 46 is electrically connectedto the plate 36 but insulated from the plate 35. Thus, the bolts 44, 46constitute the positive and negative output terminals of the alternatorrespectively. Each of the diodes is supported on a part of therespective portion of the plates 35, 36 and is surrounded by passagesthrough which air flows in use to aid cooling of the diodes. The plates35, 36 are formed from relatively thick material, and so constitute heatsinks for the diodes, and are so shaped that the diodes 37, 38, 39, 41,42, 43 lie substantially in the same plane.

The full wave rectifier further includes three phase plates 49, 51, 52,each of which is stamped from copper sheet. The phase plates 49, 51, 52are supported by the bolts 44, 45, 46 respectively and are insulatedtherefrom. Each of the phase plates includes a center region which ismounted on but insulated from the respective bolts, 44, 45, 46 andextending from the central region of each of the phase plates, inopposite directions, is a pair of integral arms. One arm of the phaseplate 49 is electrically connected to the cathode of the diode 37, whilethe other arm of the phase plate 39 is connected to the anode of thediode 43, one arm of the phase plate 51 is electrically connected to theanode of the diode 42, while the other arm thereof is connected to thecathode of the diode 38, and one arm of the phase plate 52 iselectrically connected to the cathode of the diode 39 while the otherarm thereof is electrically connected to the anode of the diode 41.Moreover, the central region of each of the phase plates 49, 51, 52includes a terminal which receives a lead whereby the phase plate iselectrically connected to the phase winding of the stator of thealternator. Each of the phase plates 49, 51, 52 includes a diodesupporting region indicated by the suffix a. The regions 49a, 51a, 52aof the phase plates carry respective field diodes 53, 54, 55 with theiranodes electrically connected to the regions 49a, 51a, 520 respectively.

The bolts 47 further serve to mount a voltage regulator 56 within theconfines of the frame 11, and the necessary electrical connectionsbetween the terminals o'f the brushes 29, the cathodes of the fielddiodes 53, 54, 55 and the voltage regulator 56 are made by way ofconductive leads.

It will be appreciated that since the brush box 24 is engaged as a pushfit with the frame 11, then it can be easily detached to facilitatereplacement of the brushes 29.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is:

l. A dynamo electric machine, including, a frame supporting a pair ofbearings, a rotor shaft journaled for rotation in said bearings, andcarrying a rotor assembly, one end of said rotor shaft extending beyondone of said bearings, and carrying a slipring assembly, there being abrush assembly supported by the frame of the machine, the brushes of thebrush assembly engaging said slipring assembly, said one end of saidrotor shaft being formed with an axial bore of generally cylindricalform, and said slipring assembly including a spigot which is engaged insaid bore to retain said slipring assembly on said shaft, said spigotbeing so shaped that at least one passage is defined between the spigotand the wall of the bore in the rotor shaft, at least one of theconnecting leads of the slipring assembly extending through said hearingwithin said passage.

2. A machine as claimed in claim 1 wherein said bore is of circularcross section and said spigot is of cruciform cross section so as todefine four passages with the wall of said bore, two connecting leads ofthe slipring assembly extending through said bearing within two of saidpassages respectively.

3. A machine as claimed in claim 1 wherein said slipring assembly is anend face slipring assembly.

4. A machine as claimed in claim 1 wherein said spigot is aninterference fit in said axial bore, and there is provided a spring clipwhich engages said spigot and the wall of said bore, and aids theinterference fit between the spigot and the wall of the bore inretaining the slipring assembly in position.

5. A dynamo electric machine including a frame supporting a pair ofbearings, a rotor shaft journaled for rotation in the bearings andcarrying a rotor assembly, one end of said rotor shaft extending beyondone of said bearings, and carrying a slipring assembly, there being abrush assembly supported by the frame of the machine, the brushes of thebrush assembly engaging said slipring assembly, said one end of saidrotor shaft being formed with an axial bore of generally cylindricalform, and said slipring'assembly including a spigot which is engaged insaid bore to retain said slipring assembly on said shaft, said spigotbeing so shaped that at least one passage is defined between the spigotand the wall of the bore in the rotor shaft, at least in accordance withsaid output.

1. A dynamo electric machine, including, a frame supporting a pair ofbearings, a rotor shaft journaled for rotation in said bearings, andcarrying a rotor assembly, one end of said rotor shaft extending beyondone of said bearings, and carrying a slipring assembly, there being abrush assembly supported by the frame of the machine, the brushes of thebrush assembly engaging said slipring assembly, said one end of saidrotor shaft being formed with an axial bore of generally cylindricalform, and said slipring assembly including a spigot which is engaged insaid bore to retain said slipring assembly on said shaft, said spigotbeing so shaped that at least one passage is defined between the spigotand the wall of the bore in the rotor shaft, at least one of theconnecting leads of the slipring assembly extending through said bearingwithin said passage.
 2. A machine as claimed in claim 1 wherein saidbore is of circular cross section and said spigot is of cruciform crosssection so as to define four passages with the wall of said bore, twoconnecting leads of the slipring assembly extending through said bearingwithin two of said passages respectively.
 3. A machine as claimed inclaim 1 wherein said slipring assembly is an end face slipring assembly.4. A machine as claimed in claim 1 wherein said spigot is aninterference fit in said axial bore, and there is provided a spring clipwhich engages said spigot and the wall of said bore, and aids theinterference fit between the spigot and the wall of the bore inretaining the slipring assembly in position.
 5. A dynamo electricmachine including a frame supporting a pair of bearings, a rotor shaftjournaled for rotation in the bearings and carrying a rotor assembly,one end of said rotor shaft extending beyond one of said bearings, andcarrying a slipring assembly, there being a brush assembly supported bythe frame of the machine, the brushes of the brush assembly engagingsaid slipring assembly, said one end of said rotor shaft being formedwith an axial bore of generally cylindrical form, and said slipringassembly including a spigot which is engaged in said bore to retain saidslipring assembly on said shaft, said spigot being so shaped that atleast one passage is defined between the spigot and the wall of the borein the rotor shaft, at least in accordance with said output.